Geochemical Journal, Vol. 52 (No. 6), pp. e21-e27, 2018
Ryu Uemura,1* Miki Uemura,1 Masaki Sano2 and Takeshi Nakatsuka3
1Department of Chemistry, Biology, and Marine Science, University of the Ryukyus, 1 Senbaru, Nishihara, Okinawa 903-0213, Japan
2Faculty of Human Sciences, Waseda University, Mikajima, Tokorozawa, Saitama 359-1192, Japan
3Research Institute for Humanity and Nature, 457-4 Motoyama, Kamigamo, Kita-ku, Kyoto 603-8047, Japan
(Received July 7, 2018; Accepted October 18, 2018; Online published November 12, 2018)
The oxygen isotope ratio (δ18O) of tree-ring cellulose provides a valuable climatic record with an annual timescale. In Japan, the cellulose δ18O records have been accumulated over the past decade. However, no long-term records have been reported for the southern subtropical island, Okinawa-jima, where many long-lived trees were burned during the Second World War and have been periodically damaged by typhoons. Here, we show a cellulose δ18O of Ryukyu Pine (Pinus luchuensis Mayr.) from the Okinawa-jima island. This δ18O data, which was obtained from a tree-disk preserved in a University Museum, cover a 95-year period before meteorological observation began on this island in 1891. The cellulose δ18O variations negatively correlate with the amount of precipitation during the rainy season, suggesting that the cellulose δ18O values are largely affected by δ18O of rainwater rather than large scale ENSO variations.
Key words: tree-ring, oxygen isotope, monsoon, paleo climate, Okinawa